Moving element body apparatus of linear motor and method for producing it

ABSTRACT

A moving element body apparatus of a linear motor is produced by punching and processing a magnetic soft iron sheet into a large number of pole pieces formed therein with a plurality of magnetic poles having a predetermined distance therebetween, building up in layers said pole pieces into at least two pole bodies, providing said pole bodies with wheel axles, and fitting said magnetic poles of said pole bodies into openings formed in a holder plate of a nonmagnetic material for receiving said magnetic poles, thereby interconnecting securely said pole bodies and fixing said wheel axles to the pole bodies.

TECHNICAL FIELD

The present invention relates to a moving element apparatus of a linearmotor and a method for producing it.

BACKGROUND OF ART

In a prior art moving element body of a linear pulse motor, as shown inFIG. 1, pole bodies 1 and 2 connected with each other on their topsurface by means of a flat plate 5 were formed on their outer ends withbearing portions 3 and 4, respectively, having a substantially U-shapedsection and said bearing portions 3 and 4 were processed on the innerwalls 3a and 4a so as to be parallel to the upper surface of a stator(not shown). Thereafter, axles 6 and 7 were fitted into the bearingportions 3 and 4, respectively, and fixed to them by a bonding agent.

The pole bodies 1 and 2 were made firstly by connecting a pole plates 1Aand 2A with each other by a connector portion 8 and press forming theminto an integral plate, and then by fixing a large number of suchintegral plates into a multilayered construction and fixing the flatplate 5 of, for example, magnet on the upper surface of it by a bondingagent, and finally, because of the necessity to separate the pole bodies1 and 2 magnetically, by cutting said connector portion 8 into movingelement bodies.

For this reason, the axles 6 and 7 would become fall off the bearingportions 3 and 4, respectively, because of, for example, deteriorationof the bonding agent, thereby making it impossible for the movingelement to move on the stator. Further, since the pole bodies 1 and 2were connected together by the flat plate 5 on their upper surfacesonly, pole teeth 1a and 2a formed on the ends of the pole bodies 1 and2, respectively, were flexible to make the clearance between the poleteeth 1a, 2a and the stator unfixed. This presented a disadvantage oflow stopping accuracy of the moving element.

Other disadvantages of the prior art linear motor moving element bodywere a large number of assembly steps required and a low productionefficiency provided.

Accordingly, an object of the present invention is to provide a linearmotor moving element and a method for producing it, capable ofsubstantially reducing the number of assembly steps of the movingelement body and increasing the stopping accuracy of the moving element.

DISCLOSURE OF INVENTION

A linear motor moving element according to the present invention ischaracterized in that a magnetic soft iron sheet is punched andprocessed into a large number of pole pieces formed therein with aplurality of magnetic poles having a predetermined distancetherebetween, which are built up in layers into two or more pole bodies,thereafter the pole bodies are provided with wheel axles, and than aholder plate of a non-magnetic material having openings for receivingsaid magnetic poles thereinto is fitted to the magnetic poles, therebysecurely interconnecting the pole bodies and fixing the wheel axles tothe pole bodies.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a prior art moving element body;

FIG. 2 is a perspective view of a pole piece according to one embodimentof the present invention;

FIG. 3 is a perspective view of pole bodies according to one embodimentof the present invention;

FIG. 4(a) to 4(c) are perspective views showing assembly of a movingelement according to one embodiment of the present invention;

FIG. 5 is a perspective view of a moving element body apparatusaccording to one embodiment of the present invention; and

FIG. 6 is a perspective view of a holder plate according to anotherembodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will first be described in detailwith reference to the drawings.

An electromagnetic soft iron sheet finished in a uniform thickness ispunched and processed by a press into a large number of poles pieces 12,as shown in FIG. 2, provided with magnetic poles 11 having pole teeth 10at ends thereof and with a flat axle portion 13A for resting the axlethereon. The magnetic poles 11 are formed to have a distance Ltherebetween.

Then, a large number of degreased pole pieces 12 are built up in layersto form two separate pole bodies 13 and 13'.

In this embodiment, unlike the prior art shown in FIG. 1, it is notnecessary to connect these pole pieces 12 together by pressing theconnector portions 8 to them and, accordingly, to cut these connectorportions 8 away at the last step.

Steps for forming the moving element body using the pole bodies thusformed will now be described with reference to FIGS. 4(a), 4(b) and4(c).

The pole bodies 13 and 13' are disposed with the distance L between themagnetic poles 11 thereof as shown in FIG. 4(a).

In this state, according to the present invention, the pole bodies 13and 13' are connected and fixed by a holder plate 20 shown in FIG. 4(b).

The holder plate 20 is made of a non-magnetic material and formed tohave openings 19 of substantially identical shape with the magneticpoles 11 and to be spaced from each other by the distance L.Accordingly, by forcibly fitting the magnetic poles 11 into the openings19 of the holder plate 20, the pole bodies 13 and 13' are connected andfixed with each other with the magnetic poles 11 are spaced from eachother by a predetermined distance (L in the illustrated embodiment). Inthis embodiment, therefore, it is not necessary to form the flat plate 5as shown in FIG. 1 or to use a bonding agent.

In this state, the surfaces of the axle portions 13A and 13'A of thepole bodies 13 and 13', respectively, and the surfaces of the pole teeth10 are polished into flat faces in parallel to the stator (not shown).

Then, axles 17 and 18 with wheels 16 secured thereto are rested on theaxle portions 13A and 13'A of the pole bodies 13 and 13', respectively.In this state, in the present invention, the axles 17 and 18 are held bya holder plate 21 shown in FIG. 4(c).

The holder plate 21 is characterized by openings 19 of substantiallyidentical shape with the magnetic poles 11 and spaced from each other bythe distance L and by bent portions 21A formed at opposite ends thereof.

Accordingly, by forcibly fitting the magnetic poles 11 into the openings19 of the holder plate 21, the pole bodies 13 and 13' are connected andfixed with each other further securely and the bent portions 21A atopposite ends of the holder plate 21 engage with the axles 17 and 18.

The moving element body shown in FIG. 5 is produced by assembling themembers in the manner described above.

The holder plate 21 may have, in place of the bent portions 21A, concaveportions 21B at opposite ends thereof for receiving the axles 17 and 18,respectively.

INDUSTRIAL APPLICABILITY

According to the present invention, as described above, since two ormore separate pole bodies have axles rested in the axle portions andthen magnetic poles are fitted into openings of a holder plate of anon-magnetic material to thereby securely connect the seaprate polebodies with each other and fix the axles to the pole bodies, it ispossible to provide important meritorious effects such as substantialreduction in assembly steps of the moving element body and increase inproductive efficiency.

Further, since flexibility of the magnetic poles is prevented by fittingthe magnetic poles into the openings of the holder plate, othermeritorious effects are provided such that a uniform clearance ismaintained between the teeth at the ends of the magnetic poles and thestator and that the stopping accuracy of the moving element isincreased.

I claim:
 1. A movable element for use in a linear electric motor,comprising:a first pole body formed of a magnetizable material andhaving a base and a plurality of magnetic poles extending outwardly fromsaid base, said magnetic poles being spaced apart by a predetermineddistance and being magnetically interconnected by said base; a secondpole body formed of a magnetizable material and spaced from said firstpole body, said second pole body having a base and a plurality ofmagnetic poles extending outwardly from said base, said magnetic polesof said second pole body being spaced apart by said predetermineddistance and being magnetically interconnected by the base of saidsecond pole body; and holder means of a non-magnetic material forholding said first and second pole bodies in a spaced apart relationshipwith a first one of the magnetic poles of said first pole body spacedfrom a first one of the magnetic poles of the second pole body by saidpredetermined distance, said holder means including surface means for atleast partially defining a plurality of openings spaced from each otherby said predetermined distance, said first one of the magnetic poles ofsaid first pole body extending through a first one of the openings insaid holder means, said first one of the magnetic poles of said secondpole body extending through a second one of the openings in said holdermeans, said first and second openings in said holder means being spacedapart by said predetermined distance to enable said holder means to holdsaid pole bodies with said first magnetic pole of said first pole bodyspaced from said first magnetic pole of said second pole body by saidpredetermined distance.
 2. A movable element for use in a linearelectric motor as set forth in claim 1 and wherein said first pole bodyincludes a plurality of interconnected layers of magnetizable materialand said second pole body includes a plurality of interconnected layersof magnetizable material which are spaced from the layers of said firstpole body.
 3. A movable element for use in a linear electric motor asset forth in claim 2 wherein a major side surface of one of the layersof said first pole body is disposed in the same plane as a major sidesurface of one of the layers of said second pole body.
 4. A movableelement for use in a linear electric motor as set forth in claim 1wherein a second one of the magnetic poles of said first pole bodyextends through a third one of the openings in said holder means, asecond one of the magnetic poles of said second pole body extendsthrough a fourth one of the openings in said holder means, said firstand third openings in said holder means being spaced apart by saidpredetermined distance, said second and fourth openings in said holdermeans being spaced apart by said predetermined distance.
 5. A movableelement for use in a linear electric motor as set forth in claim 1further including:a first axle adjacent to said first pole body; and asecond axle adjacent to said second pole body, said first and secondaxles having parallel longitudinal axes; said holder means includingfirst axle retaining means for cooperating with said first pole body tohold said first axle against movement relative to said first pole bodyin a direction transverse to the longitudinal axis of said first axle,said holder means including second axle retaining means for cooperatingwith said second pole body to hold said second axle against movementrelative to said second pole body in a direction transverse to thelongitudinal axis of said second axle.
 6. A movable element for use in alinear electric motor as set forth in claim 5 further including aplurality of wheels each of which is connected with an end portion ofone of said axles.
 7. A movable element for use in a linear electricmotor as set forth in claim 6 further including:a first axle adjacent tosaid first pole body; and a second axle adjacent to said second polebody, said first and second axles having parallel longitudinal axes;said holder means including a first portion having a length which isless than the distance between the longitudinal axes of said axles and asecond portion having a length which is greater than the distancebetween the longitudinal axes of said axles, said first axle beingdisposed between said first pole body and said second portion of saidholder means, said second axle being disposed between said second polebody and said second portion of said holder means.
 8. A movable elementfor use in a linear electric motor as set forth in claim 7 wherein:saidfirst and second openings in said holder means extend through said firstand second portions of said holder means, said first one of the magneticpoles of said first pole body extending through said first and secondportions of said holder means at a location which is between parallelplanes extending through the longitudinal axes of said axles in adirection perpendicular to a plane containing the longitudinal axes ofsaid axles, said first one of the magnetic poles of said second polebody extending through said first and second portions of said holdermeans at a location which is between the parallel planes.